Rapetti Luca, Galassi Gianluca, Rota Graziosi Andrea, Crovetto Gianni Matteo, Colombini Stefania
Dipartimento di Scienze Agrarie e Ambientali-Produzione, Territorio, Agroenergia, Università degli Studi di Milano, 20133 Milan, Italy.
Animals (Basel). 2020 Feb 13;10(2):299. doi: 10.3390/ani10020299.
In view of better environmental sustainability, livestock diets must not exceed protein requirements, as often happens with lactating goats reared in semi-intensive systems. The aim of this experiment was to verify in real-breeding conditions the influence of two diets with different protein contents (% crude protein (CP) on dry matter (DM)): 16.0 (high-protein diet; HP) vs 12.2 (low-protein diet; LP) on milk production in dairy goats. The diets differed only in the replacement-in the LP diet-of 250 g soybean meal with 250 g maize grain meal. Twenty-three Alpine goats were divided into two groups and used in a cross-over feeding trial for 2 months. Animals were weighed at the beginning of each month of the trial, and feed intake and milk yield and composition were recorded weekly. HP and LP did not differ statistically for milk yield and composition (3.32 vs 3.42 kg milk/d, 3.21% vs 3.27% fat, 3.31% vs 3.27% protein for HP and LP, respectively), but the HP diet determined a higher milk urea content (51.2 vs 36.6 mg/dL, < 0.001) and a worse efficiency of nitrogen utilization (28.0% vs 37.2%). In conclusion, the LP diet resulted in a reduction of urinary nitrogen excretion by 28% and of the feed cost by about 10%.
鉴于更好的环境可持续性，家畜日粮绝不能超过蛋白质需求，半集约化养殖系统中饲养的泌乳山羊常常出现这种情况。本试验的目的是在实际养殖条件下，验证两种不同蛋白质含量（粗蛋白（CP）占干物质（DM）的百分比）的日粮：16.0（高蛋白日粮；HP）与12.2（低蛋白日粮；LP）对奶山羊产奶量的影响。两种日粮的差异仅在于LP日粮中用250克玉米谷物粉替代了250克豆粕。将23只阿尔卑斯山羊分为两组，进行为期2个月的交叉饲喂试验。在试验的每个月初对动物进行称重，每周记录采食量、产奶量和奶成分。HP和LP在产奶量和奶成分方面无统计学差异（HP和LP分别为3.32千克/天和3.42千克/天的奶产量，3.21%和3.27%的脂肪含量，3.31%和3.27%的蛋白质含量），但HP日粮导致更高的乳尿素含量（51.2毫克/分升对36.6毫克/分升，<0.001）和更低的氮利用效率（28.0%对37.2%）。总之，LP日粮使尿氮排泄减少了28%，饲料成本降低了约10%。
